The use of bladders as contents containers and propellants in aerosols is becoming more common, particularly since commonly used fluorochloro-carbon propellants have been shown to be harmful to the environment. Such bladders are filled by an awkward process utilising special valves supplied by the bladder manufacturers. A need has existed for a mechanism which can be used by all aerosol manufacturers with existing equipment and which can be used on any bladder and any aerosol can. Such a mechanism should be sufficiently versatile that it can be used for either "under the cap" filling or for "through the valve" filling.
Until recently, aerosols were pressurised by injecting the propellant through the valve at the top of the aerosol--a slow and inefficient process. Latterly, a process has been developed of filling aerosols with both working fluid and propellant under the "cap", in a pressurised environment. Unfortunately, this more modern efficient approach has not been available for filling bladder type aerosols. Such aerosols continue to be filled "through the valve".